1. Field of Invention
The present invention relates to a display device such as a liquid crystal projector or other display device for displaying an image based on for example a video signal.
2. Description of the Related Art
A liquid crystal projector is a projector device using a spatial light modulator using a liquid crystal material (hereinafter referred to as a “liquid crystal panel”). In a liquid crystal projector, the liquid crystal panel itself does not emit light. Therefore, a liquid crystal projector combines a liquid crystal panel and a light source and emits light to the liquid crystal panel to illuminate it. Then, it applies a video signal to the liquid crystal panel and projects the image formed by the liquid crystal panel onto a screen by a projection lens. A liquid crystal projector having such a configuration enables a small sized, highly efficient projector device to be realized.
Liquid crystal materials include materials by nature changing the polarization of incoming light in accordance with the applied electric field (light modification characteristic). As liquid crystal panels, there are many panels modulating light by utilizing this property. For this reason, the light striking a liquid crystal panel must be linearly polarized (p-polarized or s-polarized) in a certain direction. The light emitted from the liquid crystal panel is rotated in its polarization direction according to the video signal applied to the liquid crystal panel. Therefore, a polarizer is arranged as a photodetector on an emitting side of the liquid crystal panel in order to modulate the light.
Further, as a liquid crystal projector, a projector having an iris ON/OFF mode switch in order to obtain a display image which can be seen more easily according to the environment where the screen is placed has been proposed (see for example Japanese Unexamined Patent Publication (Kokai) No. 2003-107422).